Combustion engine

ABSTRACT

A multivalve internal combustion engine uses multiple inlet ports (2,3), each having a separate throttle (6), a fuel injection (7) and an intake valve (5). The individual inlet ports are positioned in such a way that they join the cylinderhead essentially in the same circumferential direction, thereby achieving a continuous unidirectional whirl in the cylinder at all engine speeds and loads. At low engine speeds, only one inlet port is opened; further inlet ports are opened progressively. The diameter of the inlet ports differ in size, whereby the first opened inlet port generates the fastest gas speed and the subsequent inlet ports generate successively slower gas speeds. Achieving an uninterrupted continuous strong whirl turbulence in the cylinder throughout the engine speed range, results in overall higher maximum power output, a clean fast burn and optimum torque characteristics using variable gas column adjustments.

BACKGROUND OF THE INVENTION

This invention concerns an internal combustion engine with at least oneexhaust valve and more than one inlet valve per cylinder, as well as amechanism for operating the valves separately.

The power of a combustion engine rises with an increase in cylindercapacity and revolutions per minute (rpm). However, with a largecapacity, the oscillating mass of the big pistons limits high rpm.Therefore, high powered engines use multiple, smaller cylinders designedfor high rpm, but subsequently suffer a loss of torque at lower rpm.

For an elastic engine characteristic with strong torque the intake portsare narrow and long, whereas for maximum power they should be relativelyshort and wide. In order to optimize the gas exchange in the cylinderfor the best engine performance at high and low rpm, several solutionshave been proposed with limited success, such as variable length intakeports, the semi-closure of a double barrel carburetor or thedisengagement of the valve lifters at partial power loads.

Another proposal on this subject is the variable valve timing with whichat different rpm the valve lift time and height can be regulated, thuschanging the valve overlapping timings. Overlapping timings between theexhaust valve closure and the inlet valve opening have been standardengineering for a long time, whereby the mass of the escaping exhaustgas column generates a tiny vacuum in the exhaust port. As the inletvalve is opened early, this vacuum sucks the slightly pressurized freshgas column into movement, resulting in an overall higher cylinderfilling grade. The longer the distance between the exhaust valve and theinlet valve, the earlier the inlet valve can be opened without fresh gasescaping through the exhaust port. This circumstance has not yet beenexploited to the fullest in multivalve engines.

The overlapping times of existing multivalve engines are very shortbecause the synchronously opening inlet valves are close to the oppositefacing exhaust valves. The advantage lies in the smaller size of thevalves which are therefore lighter, enabling higher rpm. Also thecircumference of multiple valves is bigger than with a single, evenlarger valve, enabling a higher gasflow. A single inlet valve engine hasthe advantage that through placing the valve out of the center of thecylinder axis, a very desirable, unidirectional whirl is created by theinflowing gas, resulting in a higher filling grade and a quicker,smoother burn of the gas. This advantage is lost with multivalve enginesbecause gas flowing through the side-by-side valves tends to form arolling collision turbulence, causing slower and irregular burn patternsat various, especially high rpm, resulting in spontaneous detonation. Adesirable unidirectional whirl can be achieved with multivalve enginesat partial power when one of the intake ports is closed; but as soon asthe adjacent port is opened for power increase, the whirl collapses andchanges into an aforesaid collision turbulence.

Furthermore, present high performance use long valve shafts order todirect the intake ports as straight as possible to the inlet valves sothat the gas flows at a steep angle past the valve evenly around theopening gap. However, this induces a small vortex beneath each valvewhich again disturbs the desirably even swirl within the cylider.Furthermore, with longer valve shafts the oscillating mass rises, whichis contrary to the aim of attaining high rpm.

SUMMARY OF THE INVENTION

The object of the herewith presented invention is the design of amultivalve engine where the intake gas flow is controlled in such a waythat an even unidirectional swirl into the cylinder is achieved at anygiven engine speed, thereby enhancing the filling grade with asubsequent power increase, thereby also aided by long overlapping timesbetween the exhaust and inlet valves. This even unidirectionalturbulence attains a fast, clean burn of the gas particles which delayspontaneous detonation, achieving higher rpm for maximum power output;however, the engine also has strong torque characteristics at low rpm.And in respect of reaching high rpm through light mass, the valves arekept relatively short.

In the preferred construction of the cylinderhead multiple, separateintake ports, at least one port joins the cylinderhead essentially fromthe top and at least one port joins at an angle from the side; wherebyevery further port joining either from the top or from the side ispositioned in the same circumferential direction, so that a continuousunidirectional gas whirl is achieved in the cylinder. Therefore two,three or even four intake ports per cylinder can be utilized which arespread essentially at the same angle intervals around the cylinderhead.It is possible to place two intake ports leading to the cylinderheadfrom the top and two intake ports leading at an angle from the side,but, they always join the cylinderhead in a more or less equivalentdistinct circumferential direction so that the gas flow enters thecylinder in a uniform swirling manner, thus creating the desiredturbulence.

Because every intake port has its own independent but interacting airthrottle and fuel supply, the carburation is optimized and permits therealization of running the engine according to the procedure of thisinvention; whereas for low rpm at least one intake, port is opened viaits throttle and during an increase in rpm the other intake ports openvia their individual throttles respectively at set intervals.

In order to achieve a maximum valve overlapping time the engine operateswith different valve overlapping timings between the intake and exhaust,whereby the first opening inlet valve has the longest overlapping timewith the furthest positioned, latest closing exhaust valve.

There can be a provision for one or also two exhaust valves percylinder, though for each cylinder row the exhaust ports are located onthe same side. Known multivalve engines with whirl characteristics have,if seen from above, intake and exhaust ports in a cross-over positionfor each cylinder, creating an intricate construction.

In a practical development, the intake ports have different sizedcross-sections in order to generate different gas speeds. As the rpmbuild up, the individual inlet ports with gradually lower gas speeds areopened additionally in sequence. This optimizes the gas flow into thecylinder at various piston stroke positions and stroke speeds and thegas swirl does not decelerate even at maximum piston stroke. Thecombined results of the aggregation of individual variable ports arehigh peak power with excellent torque characteristics.

Further details and advantages of the invention will become from thefollowing description, with reference to the accompanying drawings,which describe the invention purely by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematic and diagrammatic presentation of a three-valve is acylinderhead with appertaining ports;

FIG. 2 is a view from the top of the cylinderhead as shown in FIG. 1,without throttles and injections;

FIG. 3 is a view from the top of a schematic three-valve cylinderheadwith a different configuration of the valves and ports;

FIG. 4 is a view from the top of a schematic four-valve cylinderhead;

FIG. 5 is a view from the top of a schematic four-valve cylinderheadwith a different configuration of the valves and

FIG. 6 is a view from the top of a schematic five-valve cylinderhead.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to FIG. 1, a first intake port (2) joins the cylinderhead (1)of a combustion engine cylinder (not shown) essentially from the top anda second intake port (3) joins at a slanting angle from the side whilepointing into a circumferential direction, so that the gas flow entersthe cylinder in the form of a whirl shown by the arrows (4). Both intakeports are closed by valves (5). Furthermore, each intake port has athrottle (6) and a fuel supply (7) which interact together. The amountof fuel supply depends on the position of the air throttle. At low rpmthe throttle of only one inlet port is opened, at higher rpm the secondone opens in addition.

Opposite to the intake ports (2) and (3) an exhaust port (8) is locatedwith an exhaust valve (9). The valve heads of the inlet valves (5) andthe valve head of exhaust valve (9) lie slanted at an angle in relationto the cylinder head. This arrangement is advantagous for the gas flowdirection, whereas the slanted inlet valve heads guide the gas flow insuch a manner that it enters the cylinder in the form of a whirl.Therefore, the intake ports do not have to be directed steeply towardsthe valve heads, enabling the valves to be kept shorter and thereforelighter, which results in higher rpm and a compact cylinder head size.

It is also apparent in FIGS. 1 and 2 that the valves which stand at anangle to each other are activated by two overhead camshafts, not shownhere.

The same principle detailed in FIGS. 1 and 2 applies to the otherarrangements shown in FIG. 3-6, whereas to simplify the illustration thethrottles and fuel supplies in the intake ports have been omitted. Thearrangement in FIG. 3 differs from the earlier described one in thatboth intake ports essentially join the cylinder head from the topwhereby one inlet valve and on exhaust valve are located side by-sideand are activated by the same camshaft and the second inlet valve islocated opposite and activated by a separate camshaft.

For the arrangement in FIG. 4 two exhaust valves use a joint exhaustport (8a). With two exhaust valves, one closes later than the other. If,for instance the left exhaust valve (9) in FIG. 4 closes later, then theintake port (2) has an earlier valve opening timing because it is thefurthest from the last closing exhaust valve (9). This enables longervalve overlapping times.

The arrangement in FIG. 5 depicts only one exhaust port (8) and exhaustvalve (9), but additionally to the two intake ports described in FIG. 1,it has a third intake port (10).

The arrangement in FIG. 6 has an additional fourth intake port (11)whereas the ports and their appertaining valves stand more tightlyaround the cylinder head, but in any case in such a way that thedirection of the ports forces a clockwise whirl into the cylinder;meaning that the slanting ports join the cylinder head in the samecircumferencial direction. The valves of the individual intake ports andthe single exhaust port are positioned in two groups at an angle to eachother, so that they can be activated by two camshafts.

With a multitude of intake ports, each port has a different sizedcross-section in order to generate different gas speeds. The intake portwhich opens first at low rpm is highest gas flow speed. In thesuccessively later opening intake ports the gas flow speeds arerespectively slower, but the pressure is higher. This optimizes the gasflow into the cylinder at various piston stroke positions and strokespeeds and the gas swirl does not decelerate even at maximum pistonstroke.

Summing up, a multivalve engine with specific directional intake portscan achieve an uninterrupted whirl in the cylinder, with a torqueenhancing gas column adjustment, also long valve overlapping timings aswell as relatively short valves; all of which result in an optimum fuelcarburation by way of an individual throttle and fuel injection for eachintake port, besides a largest possible filling grade caused by longoverlapping timings and an rpm-related regulation of the gas columnmass; further an optimal quick and clean burn caused by the stronguniform turbulence throughout the torque range and furthermore a higherpeak power with good torque characteristics by way of sequencing theport openings.

I claim:
 1. A combustion engine with at least one exhaust valve and more than one inlet valve per cylinder, wherein a separate intake port is assigned to each inlet valve and each intake port is controlled by a individual air throttle and fuel supply, wherein of the multiple separate intake ports at least one port joins the cylinderhead from the top and at least one port joins in an angle from the side; whereby every further port joining either from the top of from the side is positioned in the same circumferential direction so that a continuous unidirectional gas whirl is achieved in the cylinder.
 2. A method of operating a combustion engine which includes at least one exhaust valve and more than one inlet valve per cylinder, an intake port for each inlet valve, said intake ports having differing diameters, an individual air throttle and fuel supply for each intake port, at least one intake port joining the cylinder head from the top and at least one intake port joining the cylinder head at an angle from the side, each further intake port joining either from the top or the side and being positioned in the same circumferential direction so that a continuous unidirectional gas flow can be achieved in the cylinder, the method including opening the air throttle of only one intake port at low rpm, and gradually opening at set timings the throttles of the other intake ports with rising rpm, the intake port which is furthest from the exhaust valve being opened first, the diametrically different sized intake ports which generate different gas speeds being opened successively.
 3. A method according to claim 2, wherein the engine is operated with different overlapping valve timings between intake and exhaust, whereby the first opening inlet valve has a longer overlapping time with the furthest positioned, latest closing exhaust valve than the other inlet valves. 